Jaw deformity
The jaws and subsequently the whole facial structures grow in an altered fashion, resulting in long faces, constricted arches, tooth crowding, a narrowed nasal airway passage, and an altered head posture. The lower jaw remains too far behind in its growth, producing a small chin, dental malocclusion, a large overjet, and an unfavorable profile. If the mouth breathing is addressed, these children can often be treated for their malocclusions and skeletal growth discrepancies by a dentist or orthodontist who follows a functional - orthopedic approach.

Compromised airway
Caused by: 1. the lower jaw being positioned too far back, along with the tongue, thereby constricting the upper airway. 2. Enlarged tonsils and adenoids due to chronic allergies may be the primary cause for mouth breathing, however mouth breathing in itself will also cause a further increase in tonsil size, thus constricting the airway to such an extent, that normal nasal breathing becomes an impossibility.

Altered head, neck and body posture
The unnatural and unphysiological process of breathing through the mouth, which in many children looks like they are "gasping" for air, produces a reflex forward head posture. This puts a large load on the upper back and neck muscles, which if sustained, will cause permanent posture changes, such as abnormal curvatures in the cervical and thoracic vertebrae, and an altered shoulder posture. Ultimately, we see a domino effect affecting hips, knees and feet. In adults, Jaw joint dysfunction (TMJ problems).

Bad breath and gum disease
Caused by the shift in the bacterial flora in the mouth.

Lowered immune system and poor health
Nasal breathing produces a tissue hormone that regulates normal blood circulation. It also filters, warms and moisturizes the air. The lack of oxygen in mouth breathers, who usually snore at night and struggle for air, weakens the immune system, disrupts deep sleep cycles, and interferes with growth hormone production.

Obstructive sleep apnea (OSA)
In newborns, this is thought by many researchers to be related to SIDS, or Sudden Infant Death Syndrome. In children, this is manifested as snoring, bed-wetting, poor quality of sleep, obesity, and ultimately behavioral symptoms resembling ADHD.
In adults, OSA is a silent killer. Snoring is a manifestation of a blocked airway, which in essence is a milder version of sleep apnea. Most snorers, however, may not be aware that they may be suffering from OSA. On average, snorers are more likely to suffer from cardiovascular disease and stroke, and carry an increased risk for obesity, high blood pressure, stroke, severe obstructive sleep apnea, and diabetes.

Poor performance
The same lack of oxygen and other hormonal factors make these children tend to be overweight, tired, and not perform well at school. Physically they are not athletic.

Mouth breathing in children should be addressed as soon as possible by consulting a physician, a dentist, a myofunctional therapist or an ENT specialist, who are experienced in treating this condition.